Understanding the Omegas.
In plants, linolenic, linoleic, and oleic acids provide the heart-healthy Omegas. The number following "Omega-" represents the position of the first double bond, counting from the terminal methyl group on the molecule. Omega-3 fatty acids are derived from linoleic acid, Omega-6 from linoleic acid, and Omega-9 from oleic acid. The minimum healthy intake for both linolenic (Omega-3) and linoleic (Omega-6) acid via diet, per adult per day, is 1.5 grams of each.
The Omega-3 fatty acids exist in three forms. In marine food sources, they are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Consuming these fatty acids, along with alpha-linolenic acid, or ALA, which is derived from plants and converted in the body to DHA and EPA, is associated with a reduced risk for cardiovascular disease.
The American Heart Association recommends that healthy adults eat at least two servings per week of EPA- and DHA-rich fish and/or fish oil. These consist mainly of coldwater fatty fish such as salmon, herring, mackerel, sardines, lake trout, and albacore or bluefin tuna.
Plant sources of ALA include soy products, flaxseed, walnuts, and oils extracted from flaxseed, canola seed, olives, walnuts, or soybeans. Broccoli, too, contains ALA, but in lesser amounts.
Along with Omega-3 fatty acids, Omega-6 fatty acids play a crucial role in brain function as well as normal growth and development. Also known as polyunsaturated fatty acids, they help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system.
Omega-6 also exists in several forms. The first is linoleic acid (LA), which is found in corn, safflower, soybean, sunflower, and cottonseed oil. http://www.optimal-heart-health.com/newsletter.htmlTwo other forms of Omega-6 are GLA (gamma-linoleic acid) and ARA (arachidonic acid). GLA is also found in plant based oils. ARA is found in many animal-based foods including meat, eggs, and dairy products.
Is there validity to the concern about over-consuming Omega-6 fatty acids? Our bodies have the ability to convert linoleic acid (as well as alpha-linolenic acid) into longer chain fatty acids which lead to the production of eicosanoids. Eicosanoids, depending on their source, can have positive and negative influences on our bodies. They may slow intravascular clotting, which helps to prevent heart attacks and strokes. They can suppress inflammation, preventing us from overreacting to allergens. They may dilate blood vessels, reducing hypertension and increasing good blood delivery. They can control cell growth, slowing the rapid growth of cancer cells.
Yet dietary ARA may increase blood clotting, which leads to heart attack and stroke. Also, any suppression of the immune system leaving us more open to infection. http://www.healthychoicenaturals.com/p-65-ULTMEGA.aspx?affiliateid=10265Generally speaking, the eicosanoids produced by an overabundance of Omega-6 tend to produce the negative affects, not the positive. Americans, by some estimates, consume 10 times the recommended amounts of ARA. Limiting consumption of animal products may be one way to curb the overabundance of Omega-6s in your diet.
A healthy diet contains a balance of Omega-3 and Omega-6 fatty acids. Omega-3 fatty acids help reduce inflammation, and some Omega-6 fatty acids tend to promote inflammation. The typical American diet tends to contain 14 to 25 times more Omega-6 fatty acids than Omega-3 fatty acids.
The Mediterranean diet, on the other hand, has a healthier balance between Omega-3 and Omega-6 fatty acids. Many studies have shown that people who follow this diet are less likely to develop heart disease. The Mediterranean diet does not include much meat (which is high in Omega-6 fatty acids) and emphasizes foods rich in Omega-3 fatty acids, including whole grains, fresh fruits and vegetables, fish, olive oil, garlic, as well as moderate wine consumption.
The Good News on Omega-6
An international research team from South Korea, Japan, and the U.S., supported by the National Institutes of Health, has found that serum Omega-6 fatty acids and bad lipoprotein levels in middle-aged men were inversely proportional.
The researchers looked specifically at over 1,000 participants' linoleic acid (LA) and arachidonic acid (ARA) levels alongside the lipoprotein subclasses VLDL, LDL, and HDL. Both blood serum LA and ARA were inversely associated with high levels of very-low-density lipoprotein (VLDL) and total LDL ("bad cholesterol"). Linoleic acid and ARA were associated with high concentrations of HDL ("good cholesterol"). These associations were consistent across the population groups.
The bottom line is that there are several different types of Omega-6 fatty acids, and not all promote inflammation. Most Omega-6 fatty acids in the diet come from vegetable oils, delivered to the body as LA. Some studies show that taking gamma linolenic acid (GLA), a type of Omega-6, for six months or more may reduce symptoms of nerve pain in people with diabetic neuropathy. People who have good blood sugar control may find GLA more effective than those with poor blood sugar control.
Interestingly, clinical studies suggest that children with ADHD have lower levels of essential fatty acids, both Omega-6s and Omega-3s. Some studies seem to indicate that taking fish oil (containing Omega-3 fatty acids) may help reduce ADHD symptoms, though the studies have not been well designed. Studies that used evening primrose oil have found it was no better than placebo at reducing symptoms.
There is some preliminary evidence that GLA may help reduce high blood pressure, either alone or in combination with Omega-3 fatty acids EPA and DHA (as noted previously, found in fish oil). In one study, men with borderline high blood pressure who took 6 grams of blackcurrant oil had a reduction in diastolic blood pressure compared to those who took placebo.
Do not take Omega-6 supplements if you have a seizure disorder because there have been reports of these supplements causing seizures. Several reports describe seizures in people taking evening primrose oil. Some of these seizures developed in people with a previous seizure disorder, or in people taking evening primrose oil in combination with anesthetics. People who plan to undergo surgery requiring anesthesia should stop taking evening primrose oil two weeks ahead of time. Borage seed oil, and possibly other sources of GLA, should not be taken during pregnancy because they may harm the fetus and induce early labor. Avoid doses of GLA greater than 3,000 mg per day. At that level, an increase in inflammation may occur.
Laboratory studies suggest that Omega-6 fatty acids, such as the fat found in corn oil, promote the growth of prostate tumor cells. Until more research is done, health care professionals recommend not taking Omega-6 fatty acids, including GLA, if you are at risk of or have prostate cancer.
A Word About Omega-9 (Oleic Acid)
Omega-9, again, is considered essential but the human body can manufacture a limited amount. Monounsaturated oleic acid lowers heart attack risk and arteriosclerosis, and aids in cancer prevention. You can find Omega-9 in olive oil, olives, avocados, almonds, peanuts, sesame oil, pecans, pistachio nuts, cashews, hazelnuts, and macadamia nuts. One to two tablespoons of extra virgin or virgin olive oil per day should provide sufficient oleic acid for adults. However, the "time-released" effects of obtaining these nutrients from nuts and other whole foods is thought to be more beneficial than consuming the entire daily amount via a single oil dose.
The Omegas are a powerful source of good health and, like much of what we find available on our plates, once properly understood, can be used as part of a delicious and heart-healthy diet that offers the full gamut of protective benefits.
Am. J. Clin. Nutrition, 2010, Vol. 91, No. 5, pp. 1195-1203, http://www.ajcn.org/cgi/content/abstract/91/5/1195
University of Maryland Medical Center, http://www.umm.edu/altmed/articles/Omega-6-000317.htm
Harvard Women's Health Watch, 2010, Celeste Robb-Nicholson, MD
Harvard HealthBeat, August 3, 2010
Optimal Heart Health, http://www.optimal-heart-health.com/Omega_3.html
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|Title Annotation:||long-chain polyunsaturated fatty acids, omega-3 and omega-6|
|Publication:||Running & FitNews|
|Date:||Jul 1, 2010|
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